1. Field of the Invention
The present invention relates to an intelligent electrical distribution grid monitoring system and method that includes a network of sensors that communicate via auto discovery and mesh technology. Each sensor is inductively powered from the electrical conductor and adaptively communicates via a radio, via the electrical conductor, or both simultaneously.
2. Description of Related Art
The electric distribution grid in North America is characterized by aging infrastructure and outdated technology at a time when digital society demands an increased quantity and more reliable electrical power. As the investment cycle within the electricity distribution industry reaches a critical juncture for reinvestment in and optimization of the existing infrastructure, there is enormous pent-up demand to apply computer and electronics technologies in an industrial sector that has lagged the advancements made in the telecommunications, medical, aerospace and manufacturing industries.
Very little automation or monitoring typically exists between the customer meter and an electrical substation, making it difficult to quickly identify the cause and location of an electrical distribution problem, e.g., an outage, without manual dispatch of field crews. Additionally, planning and maintenance engineers in the electric utilities typically have limited information about the behavior of a circuit to drive the best decisions for circuit upgrade/rehabilitation tasks, and determining upgrade or replacement of equipment.
An electric utility may have Supervisory Control and Data Acquisition (SCADA) capability allowing it to have centralized remote monitoring of circuit load immediately exiting the substation and perhaps a midpoint circuit reading. Very few electric utilities have widely deployed SCADA systems, and those that do are only provided with circuit level information (entire circuit faulted and open) and cannot discern a fault location along the many miles a circuit typically spans. The utility depends on notification to their call center from customers to determine the location of damaged equipment during a power outage. Additionally, they will usually call customers to confirm restoration of power.
Electrical distribution circuits are prone to temporary faults such as nearby lightning strikes, wind-borne debris, small animals climbing insulators, and the like. With a conventional circuit breaker or fuse, a transient fault opens the breaker or blows the fuse, de-energizing the line until a technician manually recloses the circuit breaker or replaces the blown fuse. Automatic reclosing devices (autoreclosers) often make several pre-programmed attempts to re-energize the line. If the transient fault clears, the circuit breaker will remain closed and normal operation of the power line will resume. If the fault is permanent (downed wires, tree branches lying on the wires, etc.) the autorecloser will exhaust its pre-programmed attempts to re-energize the line and remain tripped off until manually commanded to try again. Ninety percent of faults on overhead power lines are transient and can be cleared by autoreclosing, resulting in increased reliability of supply.
Repeated manual closings into a permanent fault stress the circuit components, but this troubleshooting method is frequently employed by technicians.
If the fault cannot be cleared by automated or manual closing into the fault, the next option is to send a troubleshooter into the field to identify where the problem/fault is located. If the troubleshooter can fix the problem upon arrival they will. If additional crews are required, the troubleshooter notifies the Operations Center dispatcher to send the appropriate crew (tree crew, underground crew, substation crew, etc). When this situation exists, outage duration usually exceeds the 2 hour tolerance level of most customers. Service restoration is confirmed at the Operations Center via SCADA, through the automated distribution system, or by contacting customers. Currently, no automated system notification of power restoration exists throughout the distribution system.
Additional devices may provide information on the location of a fault. So-called Fault Circuit Indicators (FCIs) have been used to identify when they have experienced a fault. FCIs are stand-alone devices and require visual inspection to determine their status via driving by the FCI location and looking for a color coded or blinking lighted indicator.